冀东、五台和吕梁地区条带状铁矿的稀土元素特征及其地质意义.pdf

第24卷第5期
现代地质
Vol 24 No 5
2010年10月
CFOSCIENCE
ct.2010
冀东、五台和吕梁地区条带状鉄矿的稀土元素
特征及其地质意义
李志红,朱祥坤,唐索寒,李津,刘辉
(中国地质科学院地质研究所国土资源部同位紊地质重点实验室,北京100037)
摘要:详细报道了冀东、五台和吕梁地区条带状铁矿全岩样品的稀土元素分析结果。结果表明、研究区BIF具有非常
相似的特征:稀土总均较低;经页岩标准化的稀土元素配分模式均呈现轻稀土亏损、重稀土富集的特征;Y/Ho比值
较高;具有明显的Eu、Y、La的正异常,且这些特征表明研究区BIF的稀土元素来源于火山热液和海水的混合溶液。
虽然BIF均显示Eu正异常,但不同类型、不同沉积年龄BIF的销异常程度不同:与吕梁地区 Superior型铁矿相比,冀
东和五台地区的 Algoma型铁矿显示了更大的Eル正异常;并且自中太古代一新太古代一古元古代,BIF的销正异常逐渐
减小,这可能反映了随着BF沉积年龄的减小,进人到该地区海水中的高温热液流体逐渐减少;同时,研究区BF缺乏
明显的Ce负异常,可能暗示在BF沉积时海水的氧化还原状态为缺氧环境。
关键词:冀东地区;五台地区;吕梁地区;条带状铁矿;稀土元素;沉积环境
中图分类号:P618.31;P595
文献标志码:A
文章编号:1000-8527(2010)05-0840-07
Characteristics of Rare Earth Elements and Geological Significations of BIFS
from Jidong, Wutai and Liliang Area
LI Zhi-hong, ZHU Xiang-kun, TANG Suo-han, LI Jin, LIU Hui
Laboratory of soo Gey f MLR Inst o og h em of lg Scenes, Being 100037, ha
Abstract: The results of rare earth elements of banded iron formations samples from East Hebei Province
Wutai and Liliang of Shanxi Province are reported in this article. Analytic results show that the BIFS have the
similar characteristics: REE concentrations in BIFS are very low; the shale-nomalised REE+ Y patterns display
depletion of light REE relative to heavy REE,, high Y/Ho values and istinct positive anomalies of Eu, Y, and
La. These demonstrate that the BIFS are the products of chemical sedimentation from paleo-seawater with signif-
ant input of volcanic hydrothermal fluids Although BIFS are characterized by positive Eu anomalies, BIFS of
the different type and different age show different size of positive Eu anomalies. Compared with superior
BIF from Luliang area, Algoma BIF from Jidong and Wutai shows the higher positive Eu anomalies. The Eu
anomalies decreased from Middle arehean-neoarchean to Paleoproterozoic BIFS and this decrease in the pos
itive Eu anomaly with depositional age might argue for a decrease of high-temperature hydrothermal activity
The lack of negative Ce anomalies in almost of Blips samples indicates relatively low redox levels in the local
seawater.
Key words Jidong area; Wutai area; Liliang area; BIF; REE; depositional environment
规模铁矿床都形成于这一时期,其中条带状铁建
造( Banded Iron- Formation,简称BIF)型铁矿床是
前寒武纪是铁矿资源重要的成矿期,许多大我国乃至全球最重要的铁矿类型之ー。BIF在全球
收稿日期:2010-07-26;改回日期:2010-09-30;贲任编辑:威开静。
基金项目:中?地质调在局地质谲奁项(1212010911046,1212010711815)。
作者简介:李志红,女,助理研究员,1975年出生,地球化学专业,主要从事者石矿床地球化学研究。Emil: lizhi190ec, ac. cho。
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